Hmm. Well, that is nice. I do believe this would actually be better off in Experimental, considering how there is yet to be any card effect which specifically references a tag-partner.
As for the card itself, having your partner draw 2 cards is a pretty powerful effect, especially so when there is no cost. Just because the card does not affect you does not mean that its effect is not as effective. How about a revision/balancing such as the following? (You did not specify what kind of Spell it is; I am assuming it is a Normal Spell.)
During your tag-partner's next Draw Phase, your tag-partner draws 2 cards instead of 1 for their normal draw, and if they do, your tag-partner cannot draw cards by card effects for the rest of the turn.
I know that the sharp restriction may seem to "ruin" the heart and soul of the card, but honestly this is something which must be tested with to see the capabilities and potential of this card, and considering how it would only affect drawing, your tag-partner would still be able to search cards from his/her Deck or excavate.
- Dougtheloremaster likes this